OZONE ENRICHED WATER FOR DISINFECTION OF disinf… ·  · 2015-01-18OZONE ENRICHED WATER FOR DISINFECTION OF Tanks Production Area and Equipment ... Food Safety Food safety is of

OZONE ENRICHED WATER FOR DISINFECTION OF

Tanks

Production Area and Equipment Pipelines

RSW Systems Food Washing

Food Safety Food safety is of paramount importance in the food processing industry. Because of the incedence of food contamination along the entire chain of production, the need for disinfection in multiple forms and at multiple points is necessary. Growing concerns with chemical use on products and in wastewater, coupled with the need to conserve or reuse water are supporting the need for alternative sanitation technologies. Ozone is emerging as the anti-microbial technology for the 21st century and is well suited to the multiple intervention approach that is being taken today by the food industry to improve sanitation and food safety.

Ozone enriched water for Surface Sanitation Ozone is a strong oxidizing agent which makes a major contribution towards a cleaner environment and food safety. Ozone affects microbial membranes and denatures metabolic enzymes. Ozone- enriched water kills microbes effectively and is an effective biocide against:

• Bio - Film • Bacteria • Viruses • Fungi ( yeast, mold and their spores ) • Protozoa ( including cysts )

Ozone- enriched water can be sprayed directly on floors, drains, walls, wet-table equipment, tanks & piping (externally or internally) and clean rooms via a mobile or centralized system with handheld, dropdown or low pressure sprayers. Based on industry experience, the amount of time necessary to attain sanitation depends on the amount of debris found in the area to be sanitized. A general cleaning to remove heavy surface dirt is necessary to expedite the ozone sanitation process. Time estimates for proper sanitation are difficult to predict, therefore Normex recommends that the end-user uses their own sanitation efficacy testing protocol to determine necessary spray time.

Antimicrobial Action

• Causes irreversible damage to the fatty acids in the cell membrane (e.g. phosphatidylethanolamine) and cellular macromolecules, e.g. DNA.

• Biphasic death curve: an initial rapid inactivation stage followed by a slower inactivation stage. • 3000 times faster than chlorine • Bactericidal effect on Salmonellae, Staphylococcus, E. coli, etc. • Rapid and effective sporicide (Bacillus and Clostridium spores)

Antimicrobial Efficacy Results**

Organism Applied O3 Dose

O3 Dose at Nozzle (ppm)

Exposure Time (min)

Reduction

Trichophyton mentagrophytes ( ATCC 9533 )

3.0 ppm 1.85-2.25 3 6 log ( 99.9999 % )

Salmonella choleraesuis ( ATCC 10708 )

3.0 ppm 1.85-2.25 10 6 log ( 99.9999 % )

Staphylococcus aureus ( ATCC 6538)

3.0 ppm 1.85-2.25 5 6 log ( 99.9999 % )

Pseudomonas aeruginosas ( ATCC 15442 )

3.0 ppm 1.85-2.25 30 sec 6 log ( 99.9999 % )

Campylobacter jejuni ( ATCC 33250 )

3.0 ppm 1.85-2.25 3 4 log ( 99.99 % )

Listeria monocytogenes ( ATCC 7644 )

3.0 ppm 1.85-2.25 3 4 log ( 99.99 % )

Aspergillus flavus ( ATCC 9296 )

3.0 ppm 1.85-2.25 5 4 log ( 99.99 % )

Brettanomyces bruxellensis ( ATCC 10560 )

3.0 ppm 1.85-2.25 3 4 log ( 99.99 % )

Escherichia coli * ( ATCC 11229 )

3.0 ppm 2.1 30 sec 5 log ( 99.999 % )

Efficacy studies were conducted by the National Sanitation Foundation (NSF) according to: **AOAC Official Method 961.02; Germicidal Spray Products as Disinfectants Test and *AOAC Official Method 960.09, Germicidal and Detergent Sanitizing Action of Disinfectants.

Internal Sanitation of Tanks & Piping Systems For internal sanitation ozone-enriched water is directly injected into a facility’s fluid distribution network and circulated for a set duration of time. Overall chemical costs are reduced or eliminated, and overall system deterioration is reduced when using ozone enriched water rather than traditional anti microbial chemicals or hot water. Benefits Ozone enriched water has the benefit of replacing the chemicals and hot water typically used in cleaning the inside of pipelines, tanks and external surfaces. The benefits are:

• Ozone reduces chemical sanitation cost • Ozone disinfects more powerfully then most chemical disinfectants • Micro-organisms can not build up an ozone tolerance. • Ozone used properly cannot endanger the environment

Other advantages using Ozone enriched water are:

• High environmental profile as ozone leaves no chemicals or residual by-products to spoil product quality

• Ozone management systems eliminates inhalation worries

• Ozone is not harmful to the environment as chlorine • Ozone is safer than chlorine or sulphur dioxide • Ozone is generated "on-site" and does not have to be purchased or stored • Ozone does not have to be measured daily • Ozone at low levels can be measured with a simple ORP meter • Ozone at high levels can be measured with a dissolved ozone monitor

Direct Food Contact

Ozone enriched water is in the US and in many other countries used for direct contact on fruits and vegetables, raw and ready to eat meat and poultry, fish and commercial eggs. The benefits of ozone enriched water far outweigh chemical enriched water traditionally used. Testing performed by the National Sanitation Foundation, NSF, (under AOAC Methology), shows that, ozone dissolved in water can provide a 6 log reduction in as low as 30 sec. (depending on micro organism) the clew lies in the ozone dosage and holding time. Ozone enriched water leaves no chemical residue on your product and actually assist in removing pre-wash residues in some products. Ozone systems can easily be integrated into most existing conveyer lines. Our systems provide low pressure spray, and can be easily integrated into existing wash lines.

DesinfectaTM

The Normex surface sanitation system “DesinfectaTM” recirculates ozone enriched sea/freshwater for disinfection purposes. It is designed to charge a given tank of water with ozone for safe and effective disinfection of external or internal surfaces. The water circulates in a tank and ozone is added until it reaches the required ORP value for disinfection.

Normex can through its Desinfecta™ systems deliver ready to use units for sanitation of surfaces or customised units according to sanitation needs to suit the individual project.

US Government Regulatory Status USDA/FSIS – December, 2001 – “The use of ozone on meat and poultry products, including treatment of ready-to-eat meat and poultry products just prior to packaging, is acceptable,” and that there are “no labelling issues in regard to treated product.”

FDA/CFSAN – June 26, 2001- Final Rule published in Federal Register ( 21 CFR Part 173, Docket NO. 00F-1482) “ The FDA amends the food additive regulations to provide for the safe use of ozone in gaseous and aqueous phase as an anti-microbial agent on food, including meat and poultry.”

USDA/AMS – December, 2000 – Ozone is listed in the National Organic Programme Final Rule (Subsection 205.605 (b) (20) – Non-agricultural (non organic) substances allowed as ingredients in or on processed products labelled as” organic” or “made with organic (specified ingredients or food group(s))”.

FDA – November 5, 1982 – Final rule published – O3 declared GRAS for treatment of bottled water, (2) CFR §184.1563)

Cal Poly State University Ozone Research Results Summary

E.Coli 0157:H7 on Lettuce

Microorganism E. Coli 0157:H7

Medium Lettuce

Ozone Concentration in Solution

0.30 PPM

Reduction 4-Log Cycle Average at 180 Seconds

Percent Reduction 99.9999672% @ 0.30 PPM Ozone

Total Coliform on Lettuce

Microorganism Total Coliforms

Medium Lettuce

Ozone Concentration in Solution

0.15 - 0.20 PPM

Reduction 3 to 4-Log Cycle Average at 180 Seconds

Percent Reduction 99.999992% @ 0.15 PPM Ozone

E. Coli on Chicken

Microorganism E. Coli Medium Chicken

Ozone Concentration in Solution

0.15 - 0.20 PPM

Reduction 4-Log Cycle Average at 180 Seconds

Percent Reduction 99.99993% @ 0.15 PPM Ozone

Salmonella on Chicken

Microorganism Salmonella

Medium Chicken

Ozone Concentration in Solution

0.15 - 0.20 PPM and 0.30 PPM

Reduction 3 to 4-Log Cycle Average at 180 Seconds

Percent Reduction 99.999% @ 0.15 PPM Ozone 99.9999966% @ 0.3 PPM Ozone

Staphylococcus on Beefsteak

Microorganism Staphylococcus

Medium Beefsteak

Ozone Concentration in Solution

0.15 PPM

Reduction 3-Log Cycle Average at 180 Seconds

Percent Reduction 99.97778% @ 0.15 PPM Ozone

Shigella on Lettuce

Microorganism Shigella

Medium Lettuce

Ozone Concentration in Solution

0.15 and 0.30 PPM

Reduction 3 to 4-Log Cycle Average at 180 Seconds

Percent Reduction 99.957% @ 0.15 PPM Ozone 99.9995% @ 0.3 PPM Ozone

Trends in Food Science & Technology 18 (2007) S29eS35

Use of ozone in food

industries for

reducing the

environmental

impact of cleaning

and disinfection

activities

A. Pascual*, I. Llorca andA. Canut

Parque Tecnologico de Valencia, Benjamin Franklin,

5-11, 46980 Paterna, Valencia, Spain

(Tel.: D34961366090; fax: D34961318008;e-mail: [email protected])

IntroductionThe interest in ozone as an alternative to chlorine and

other chemical disinfectants in cleaning and disinfectionoperations is based on its high biocidal efficacy, wide anti-microbial spectrum, absence of by-products that are detri-mental to health and the ability to generate it on demand,‘in situ’, without needing to store it for later use.

It also has the significant advantage of being an environ-mentally friendly technology that reduces the company’senvironmental costs and facilitates their compliance withstatutory obligations.

This advantage is usually underestimated by food com-panies, but the new environmental legislation emerging inEurope, especially the IPPC Directive 96/61/EC, will drivea change in the food industry in the next years that will in-crease the interest in the use of ozone. It should be takeninto account that cleaning and disinfection operations areresponsible for the greatest environmental impacts (waterand energy consumption, wastewater, etc.) in a number offood processing plants.

* Corresponding author.

0924-2244/$ - see front matter � 2006 Elsevier Ltd. All rights reserved.doi:10.1016/j.tifs.2006.10.006

Review

The Spanish technological centre ainia is the leader ofthe OZONECIP project which has been recently fundedby the EU LIFE Programme (LIFE 05 ENV/E/000251).This project will not only evaluate the use of ozone asa powerful disinfectant for machinery and equipment, andsanitisable surfaces in general, but also analyse the environ-mental advantages of ozone and its potential considerationas a Best Available Technology (BAT) for cleaning and dis-infection in food processing plants.

Ozone as a disinfectant agentEffect of the medium on the bactericidalefficacy of ozone

Ozone effectiveness against micro-organisms depends notonly on the amount applied, but also on the residual ozone inthe medium. Residual ozone is the concentration of ozonethat can be detected in the medium after application to thetarget surface. Both the instability of ozone under certainconditions and the presence of ozone-consuming materialsaffect the level of residual ozone available in the medium.It is important, therefore, to distinguish between the concen-tration of applied ozone and residual ozone necessary foreffective disinfection. It is advisable to monitor ozoneavailability during treatment.

Pure water has the lowest ozone demand. Impurities reactwith and consume the applied ozone. Depending on the typeof substance, the demand will be greater or less. For example,according to one study, the residual ozone in ozonated watercontaining 20 ppm of Bovine Serum Albumin (BSA) was sig-nificantly lower than in deionised water or water with 20 ppmof soluble starch. As a result, the biocidal efficacy of ozonewasnot affected by the starch but was significantly reduced by theBSA (Restaino, Frampton, Hemphill, & Palnikar, 1995).

There is no consensus on the effect of temperature on thebiocidal efficacy of ozone. A fall in the temperature of theaqueous medium increases ozone solubility and stability,augmenting its availability in the medium and, conse-quently, its efficacy. A rise in temperature, on the otherhand, increases the proportion of micro-organisms de-stroyed by disinfectants. Consequently, the simultaneouscontribution of these two factors (solubility/stability andreactivity) to ozone efficacy can vary with experimentalconditions, making it difficult to predict the influence oftemperature on a particular application.

High relative humidity is required for micro-organismsto be inactivated by ozone gas. The optimum level is

S30 A. Pascual et al. / Trends in Food Science & Technology 18 (2007) S29eS35

90e95% RH, below 50% the bactericidal effect disappears(Kuprianoff, 1953).

Sensitivity of microbes to ozoneOzone is a powerful broad-spectrum antimicrobial agent

that is active against bacteria, fungi, viruses, protozoa, andbacterial and fungal spores (Khadre, Yousef, & Kim, 2001).Inactivation by ozone is a complex process that attacks var-ious cell membrane and wall constituents (e.g. unsaturatedfats) and cell content constituents (e.g. enzymes and nucleicacids). Both molecular ozone and the free radicals pro-duced by its breakdown play a part in this inactivationmechanism but there is no consensus on which of them ismore decisive. The micro-organism is killed by cell enve-lope disruption or disintegration leading to leakage of thecell contents. Disruption or lysis is a faster inactivationmechanism than that of other disinfectants which requirethe disinfectant agent to permeate through the cell mem-brane in order to be effective.

As regards the spectrum of action, each micro-organismhas an inherent sensitivity to ozone. Bacteria are more sen-sitive than yeasts and fungi. Gram-positive bacteria aremore sensitive to ozone than Gram-negative organismsand spores are more resistant than vegetative cells.

Some bacteria have innate chlorine resistance, includingbacterial spores and Cryptosporidium (Holah, 2003).Micro-organism resistance to other disinfectants have alsobeen observed, though at concentrations significantly below in-use concentrations such as that of Listeria monocytogenes toquaternary ammonium sanitizers (Lemaitre, Echchannaqui, &Michant, 1998).

Due to the mechanism of the ozone action, which de-stroys the micro-organism through cell lysis, it cannotlead to micro-organism resistance.

TaintingThere is growing concern about the residual presence of

dangerous by-products from chlorine and other chemicalswhen used as disinfectants in the food industry (Richardsonet al., 1998). If water contains organic nitrogen or free am-monia, chloramines are formed. These cause odours andtheir possible carcinogenic effect is under study. If smallamounts of phenols are present, chlorophenols can form,giving the water medicinal odours and tastes. Trihalometh-anes (THM), which are potentially carcinogenic, also ap-pear in drinking water that has been chlorinated. This isone of the reasons for the food industry’s interest in findingalternative disinfectants that do not cause this problem.Ozone is of great interest as a disinfectant, as it breaksdown quickly into oxygen without leaving residues.When it reacts with organic compounds the possible break-down by-products are aldehydes, ketones or carboxylicacids, which do not present health problems.

On-site productionOzone is generated on site and does not need to be

stored for later use. The ozone production method most

commonly used in commercial equipment is corona dis-charge. This method can employ dry air, oxygen, or a com-bination of the two. Ozone is generated by passing the feedgas between two closely spaced electrodes (one of which iscoated with a dielectric material) under a 10 kV current. Adischarge occurs when the gas becomes partially ionised,resulting in a characteristic violet glow when air is usedas the feed gas (if oxygen is used the violet color is seldomobserved) (EPRI, 2000).

ToxicityThe toxicity of ozone varies, depending on its concentra-

tion and the length of exposure. Symptoms resulting fromexposure to ozone at 0.1e1.0 ppm include headaches, drythroat, irritation to the respiratory system and smartingeyes. Exposure to 1.0e100 ppm can cause asthma-likesymptoms such as tiredness and loss of appetite. Short ex-posure times at high concentrations can cause throat irrita-tion, haemorrhage and pulmonary congestion.

In the United States, the current permissible level forozone exposure in the workplace environment is 0.1 ppm,as adopted by the Occupational Safety and Health Adminis-tration (OSHA). This is the concentration at which a suscep-tible individual may be continuously exposed to ozone undernormal working conditions for 8 h a day or 40 h a weekwithout adverse effects. The short-term exposure limit is0.3 ppm: short-term means exposure for less than 15 minnot more than 4 times a day, with intervals of at least 1 hbetween each short-term exposure (Prior and Rice, 2000).

Ozone is, therefore, a toxic gas that must be monitoredin the workplace when it is used to disinfect equipmentand installations. Nowadays, a wide variety of ozone sen-sors are commercially available to monitor levels in theworking environment. They are usually UV analysers,equipped with a cell that measures concentrations from0.1 to 100 ppm v/v, that trigger an alarm as soon as theozone concentration rises above 0.1 ppm.

Safety aspects must always be taken into account, partic-ularly when ozone is used in gas form in cold stores, roomsor closed spaces. In these situations, concentrations must beprecisely monitored at different critical points and appro-priate safety intervals before opening must be establishedin order to avoid personal health risks.

When ozone is dissolved in water for use as a disinfec-tant it is accompanied by excess undissolved gas, as noozone transfer system is 100% efficient. The excess ozonemust therefore be destroyed or converted back into oxygenbefore being released into the atmosphere. Small heatedcatalyst ozone scrubbers are usually installed for thispurpose.

Interaction with materialsOzone interaction with the equipment and surfaces to

be cleaned and disinfected is a key factor that must betaken into consideration, essentially because of the corro-sion it may cause, but also because the ozone loses itseffectiveness.

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Table 1. Summary of studies of surface disinfection using ozone

Application Treatment Micro-organism Results Author, year

Dairy biofilmson stainless steelsurface

Ozonated water,0.5 ppm for 10 min

Pseudomonas fluorescensand Alcaligenes faecalis

5.6 and 4.4 log reduction,respectively

Greene, Few, Joao, &Serafini, 1993

CIP system Ozonated water Staphylococcus aureus,Pseudomonas aeruginosaand Candida albicans

99% microbial countreduction

Lagrange, Reiprich, &Hoffmann, 2004

Mixing kettle,table top and shroud(all stainless steel)

Ozonated water,2 ppm at 10 gpmfor 1 min

Unspecified Microbial platecount reduction rangingfrom 63.1 to 99.9%(depending on surface)

Hampson, 2000

‘High-traffic’ and‘low-traffic’ floor areas

Ozonated water,2 ppm at 10 gpmfor 1 min

Unspecified Microbial platecount reductions67.0e95.6%and 84.3e99.9%, respectively

Hampson, 2000

Plastic shipping container Ozonated water,2 ppm at 10 gpmfor 1 min

Unspecified Microbial bioluminescenceassay reduction 68.8e97.4%

Hampson, 2000

Stainless steel surfaces 2 ppm ozonegas at atmosphericpressure, 22 �C and77% HR for 4 h

Escherichia coli,Serratia liquefaciens,Staphylococcus aureus,Listeria innocuaand Rhodotorula rubra

Reduction rangingfrom 7.56 to 2.41 log values

Moore, Griffith, &Peters, 2000

Stainless steel surfaces inthe presence of UHT milk

2 ppm ozonegas at atmosphericpressure, 22 �C and77% HR for 4 h

Escherichia coli, Serratialiquefaciens,Staphylococcus aureus,Listeria innocuaand Rhodotorula rubra

Reduction rangingfrom 5.64 to 1.65 log values

Moore et al., 2000

Stainless steel surfaces 2 ppm ozonegas in bioaerosolchamber at 20 �Cand 50% HRfor 1 h

Microccocus luteus 2e3 log reduction Bailey, Young, Fielding, &Griffiths, 2001

Surfaces 2 ppm ozonegas, 2 h exposure

Unknown 2 log reduction Taylor & Chana, 2000

Equipment, walls,floors, drains, tablesand conveyors, previouslywell-cleaned

Ozonated water,3.0e3.5 ppm

Trichophyton mentagrophytes,Salmonella choleraesuis,Staphylococcus aureus,Pseudomonas aeruginosa,Campylobacter jejuni, Listeriamonocytogenes, Aspergillusflavus, Brettanomycesbruxellensis, Escherichia coli

Log reductionranging from 6 to 4

Boisrobert, 2002

of wastewater is cleaning water. This is used for equipmentcleaning, e.g. line purging at product change-over, start-up,shut-down and change-over of HTST pasteurisation units aswell as some product washing.

Breweries use significant amounts of water and energyand produce wastewater and solid residues. The typicalconsumption levels of fresh water and emission levels ofwastewater for German breweries are 3.7e4.7 hl/hl beersold and 2.2e3.3 hl/hl beer sold, respectively [GermanyBAT Reference Document, 2002].

Suspended solids in the wastewater originate from thedischarge of by-products, diatomaceous earth, e.g. kieselguhr,and possible label pulp from the bottle cleaner. Nitrogen orig-inates mainly from detergents used for tank cleaning, from themalt and from additives. Phosphorus may come from thecleaning agents used. Large variations in pH may occur due

to the use of acids and caustic for the cleaning of processequipment and returnable bottles. Heavy metals are normallypresent in very low concentrations. Wear of the machines,especially conveyors in packaging lines, may be the sourceof nickel and chromium.

In the wine industry, wastewater is generated in nearlyall process steps, e.g. cleaning of containers, reactors andfilters. The highest concentrated wastewater is producedduring fermentation, fining and ageing/racking due to thewashing out of the sediments, marcs and lees. The semi-solid fractions can be separated for further dewatering, dry-ing, processing or disposal rather than being washed withwater, due to their high organic load.

Wine bottles are cleaned before filling, and consequentlywashing water enters the wastewater treatment plant or isrecycled. Even after the recovery process, the wastewater

S33A. Pascual et al. / Trends in Food Science & Technology 18 (2007) S29eS35

shows an acidic character (pH 4e6) except when causticsolutions are used in the elimination of tartrate or duringthe conditioning of bottles. The most polluting wastewaterduring wine production is generated during the fermenta-tion and racking (especially first racking) operations.

Adopting ozone in cleaning and disinfection processescan bring various advantages over commonly employeddisinfectants. Ozone breaks down quickly into oxygenwithout leaving undesirable residues. This is an advantageboth from the point of view of food safety and to improvethe quality of wastewaters by avoiding the presence ofharmful chlorine compounds. Replacing chemical productswith ozone also lowers the concentration of salts and, there-fore, the electrical conductivity of discharges.

The use of ozone can save water in comparison to otherbiocides, as it is faster-acting. Additionally, since it doesnot leave residues it does not require a final rinse to removeany residual disinfectant that might remain in the treatedmedium.

Another advantage, provided adequate microbiologicalcontrols are implemented, is that the ozonated water thathas been used for disinfection can potentially be re-usedfor the initial cleaning stages, either directly or after re-ozonation to attain the required quality.

Wastewaters are oxygenated by ozone conversion, soozone use will improve the performance of aeration tanksand biological wastewater treatment processes. This isalso an advantage from the point of view of reducing odourgeneration.

Ozone use also provides energy savings as it is normallyused at low temperatures. Finally, as it is generated ‘‘on

rack rinse can be re-ozonated and used for the first rinse,reducing water usage and disposal costs. Before installingozone, the company kept a large stock of 30% sodiumhypochlorite. Throughout the day, 100 ppm chlorine rinseswere used on equipment surfaces. Now, water containing1 ppm ozone is used. The total cost of the system was$ 73,800, but it has already reduced the $ 9000 per quarterexpenditure on hypochlorite.

Rice, Graham, and Lowe (2002) described a financialstudy conducted in an American food plant (20 processinglines operating 24 h a day, 300 days a year) that introduceda mobile ozonated water disinfection system. The new sys-tem enabled the processor to cut the previous four disinfec-tion steps to only two and thereby reduce water use from56.8 m3 to 22.7 m3. The following table shows how annualsavings of $ 18,981 were achieved.

Cost of chemicalproducts ($/year)

Wastewaterdischarges (m3/day)

Discharge tax($/m3)

Monthly dischargetax ($)

Annual dischargetax ($)

Annual total ($)

Without ozone 6000 56.775 12,702 1802 21,635 27,635With ozone 0 22.710 12,702 721 8654 8654Total annual saving 18,981

the spot’’, ozone removes the need to store hazardoussubstances which could give rise to accidents that endangerhuman and environmental health and safety.

Examples at industrial scalePlumrose USA Inc. employs ozonated water for sanitis-

ing work areas and for processing equipment used for slic-ing and packaging ham, turkey, chicken and other meats.The company has a centralised system that produces ozo-nated water on demand (28 g ozone/h) and delivers it auto-matically to the work areas through closed piping under lowpressure. As well as using ozonated water to sanitise plastictubs and stainless steel walk-in coolers, the company alsouses ozone instead of chlorine to rinse its stainless steeltransportation racks in a three-stage process. Since ozonebreaks down into oxygen, ozonated water from the final

Ozone-based disinfection methods usually entail higher in-vestment costs than methods based on other chemical disin-fectant products. However, their running costs are very lowas they only consume a moderate quantity of electricity. Asthe above example shows the savings on water, dischargetaxes and chemical products can quickly recoup the higherinitial outlay.

WineriesIn Australia, ozone is being used successfully on an in-

dustrial scale as an alternative to chlorine for disinfectingthe oak barrels used for ageing wine. The main advantagethat is stimulating a growing interest in the use of ozoneis that it is more effective for controlling certain Brettano-myces yeast species that cause off-tastes and other defectsin wines (Day, 2004).

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The corrosive effect of ozone depends on the concentra-tion employed. At high concentrations it may corrodeequipment, but such high concentrations only occur withinthe ozone generator or in the system that injects the ozoneinto the water. Most materials are compatible with ozone atmoderate concentrations of 1e3 ppm ozone.

The plastics most frequently employed in the food in-dustry perform well in the presence of ozone and theirresistance to corrosion by ozone is considered good orexcellent: PTFE (Teflon), PVDF (Kynar), PVC (rigid andflexible) and ECTFE (Halar) are mentioned in variouspublications.

Other materials that show resistance are 316L and 304Lstainless steel, particularly the former, which stands upbetter to corrosion by ozone than by chlorine accordingto some authors (Green, Smith, Knight, 1999; Singh &Singh, 1999).

However, natural rubber is highly sensitive to contactwith ozone, leading to total disintegration (Kim, Yousef, &Khadre, 2003). Silicone is resistant in the short-term butoxidises on extended exposure to ozone. Consequently, itis good practice to identify all the materials that couldcome into contact with ozone and check their potentialresistance.

Use of ozone to clean and disinfect surfaces andequipment

Ozone can be applied both as a gas and in ozonated water.Several studies have examined its efficacy by testing differenttreatments on various surfaces and micro-organisms anda number of these are listed in Table 1.

From the table it can be seen that moderate doses ofozone, between 0.5 ppm and 3.5 ppm, both in gas formand as ozonated water, are sufficient to achieve significantmicrobial reductions. These concentrations are potentiallycompatible with most plastic materials and certain typesof stainless steel used in food sector plants.

When ozone is applied as a gas, the necessary exposuretimes are considerably longer (1e4 h) than for applicationin ozonated water (1e10 min). Theoretically, increasingthe relative humidity of the space where it is applied mightincrease the efficiency of gaseous ozone, thus shorteningexposure times.

Some recent studies have examined new methods of ap-plying ozone by fogging ozonated water and charging itelectrostatically to increase the effectiveness of this tech-nique on vertical surfaces and undersides (Birks, 2003).

In practice, a custom-tailored study is recommended inorder to design a safe, efficient cleaning and disinfectionprogramme. This study should include an analysis of thesurfaces to be treated, the best way to apply the ozone,the dose to be applied and the residual ozone level to beachieved in the medium, exposure time, microbiologicalanalyses, etc. The cost of these studies as well as the capitalcost must be taken into account, and may prove

a commercial obstacle to these methods which are still rel-atively unfamiliar in the sector.

The investment costs for ozonation systems are usuallyhigher than for chlorine or other chemical products, butrunning costs are very low as the only requirement is theelectricity to produce the ozone. Ozone disinfectionmethods also save water and energy, as well as wastewatertreatment costs and discharge taxes.

In recent years, particularly in the United States, the intro-duction of ozonation equipment for food industry surfacecleaning and disinfection has made significant advances.One factor that has undoubtedly boosted this advance isthe recent FDA approval for ozone use in food treatment,storage and processing.

A significant point in its progress is the recent launch ofthe first commercial models. These are compact systems(fixed or mobile) that spray ozonated water onto open sur-faces or recirculate it through CIP systems. They have re-ceived NSF recognition after passing biocidal efficacytests using official methods.

Environmental impact of cleaning and disinfection:potential advantages of ozone

Cleaning and disinfection are essential to maintainhygienic conditions in food processing plants. However,high water and energy use and the generation of waste-waters have a significant environmental impact.

Large quantities of water are required for cleaning anddisinfection in the food industry. The wastewater profileis largely dependent on production and cleaning patterns.Wine, beer and dairy processing plants installations useconsiderable amounts of water with the amount dependingon the type and size of equipment to be cleaned and the ma-terials processed; 60e80% of the total water consumptionis used for cleaning activities.

Cleaning and disinfection produces wastewater. Thistypically contains soluble organic material, FOG, SS, nitrate,nitrite, ammonia and phosphate from product remnants andremoved deposited soil. It also contains residues of cleaningagents, e.g. acid or alkali solutions. In principle, the cleaningand disinfection agents that are used are discharged via thewastewater, either in their original state or as reactionproducts.

Wastewater may have a high or low pH due to the use ofacid and alkaline cleaning solutions. The use of phosphoricand nitric acids will increase the phosphate and nitratecontent of the wastewater. Badly designed systems and in-adequate product removal prior to the start of cleaning maylead to large quantities of product entering the cleaningwater.

Wastewater is the main environmental issue in the dairysector (0.9e25 m3/t processed milk [European Dairy Asso-ciation, 2002]). The sector uses a vast amount of water, andgenerates a huge amount of wastewater in maintaining therequired level of hygiene and cleanliness (between 25 and40% of the total water consumed). The largest proportion

S34 A. Pascual et al. / Trends in Food Science & Technology 18 (2007) S29eS35

A further, no less important advantage is that changingto ozone disinfection avoids the presence of substancessuch as Trichloroanisol (TCA), which is responsible forcork taint problems in many wines (Franson, 2004). Ozoneis also considered to provide cost-savings as it reduces theneed to buy and store chlorine.

Ozone is increasingly used in Australian wineries andvarious ozonation system suppliers are already marketingequipment specifically designed for this application. Assome wine-makers have found, ozone doses that are effec-tive to control microbes in the barrels do not affect the qual-ity of the wine.

The system for cleaning and disinfecting the barrels withozone consists of two stages. The first stage uses high pres-sure hot water to dissolve the tartrates and blast the barrelsclean. The second is a cool rinse with ozonated water whichsanitises and shrinks the pores in the oak and cools the bar-rels. Three factors affect how long the treatment with ozo-nated water should last: the type and age of the barrel, itsmicrobial load and the concentration of ozone in the treat-ment water, which is typically 2.0e2.5 ppm for the equip-ment used in these cellars.

The use of ozone in the wine business is not confinedto oak barrels. After cleaning, ozonated water is sprayeddirectly onto floors, sumps, walls, the inside and outsideof tanks, fruit bins and other wettable surfaces in the winery.

It is also used for the disinfection stage in CIP systeminstallations. The ozonated water is recirculated aroundthe equipment using a closed loop of pipe or hose. Theozone is used up as it reacts with the organic matter inthe equipment. When ozone is again detected in the waterleaving the equipment this means that all the organic matterhas been oxidised. To ensure that sterility has beenachieved, ozonated water is usually left to recirculate fora few minutes longer.

Other disinfection-related wine industry applications ofozone that are emerging are: treating well water to removemicro-organisms, organic matter, iron and manganese;using ozone gas to replace SO2 in barrel storage; bottlewashing as in other drink industries; or treating wastewater.

Equipment for ozone disinfectionCurrently, three ozonation equipment suppliers have al-

ready received National Sanitation Foundation (NSF) regis-tration of their systems for disinfecting surfaces withozonated water. They are all identified in the NSF WhiteBook� Listing of Proprietary Substances and NonfoodCompounds (http://www.nsf.org/usda). As a result of thisregistration, food processors can consider these systemsas ‘USDA approved’ for sanitation of food-contact andnonfood-contact surfaces. This is particularly important asit enables plants operating under the USDA poultry, meat,shell egg and egg products inspection programmes to intro-duce this application of ozone.

Boisrobert (2002), explains the features of two NSF-registered ozonated water surface sanitation systems and

gives the microbiological results of antimicrobial efficacytests performed by the Toxicology Group, LLC, a divisionof NSF.

One of the models is a mobile system that provides a10-gpm water spray with a 3.0e3.5 ppm ozone dose. It isdesigned to sanitise equipment, walls, floors, drains, tables,conveyors, containers, tanks and barrels. The other, whichis also mobile, recirculates ozonated water at 35 gpmwith a 3.0 ppm ozone dose through tanks ranging in sizefrom 50 to 2500 gallons. It is designed for CIP and COP(clean-out-of-place) processes.

The methods used for the tests were AOAC OfficialMethod 960.09, Germicidal and Detergent Sanitizing Ac-tion of Disinfectants; and AOAC Official Method 961.02,Germicidal Spray Products as Disinfectants.

The micro-organisms studied had an ozone dose applica-tion of 1.85e2.25 ppm from the nozzle, except for Escherichiacoli where the ozone dose was 2.1 ppm. The results obtainedsubstantiate the efficacy of these systems for sanitisingpreviously cleaned non-porous surfaces, including processingequipment, which came into contact with food.

Micro-organism Log reduction

Trichophyton mentagrophytes (ATCC 9533) 6Salmonella choleraesuis (ATCC 10708) 6Staphylococcus aureus ATCC 6538 6Pseudomonas aeruginosa ATCC 15442 6Campylobacter jejuni (ATCC 33250) 4Listeria monocytogenes (ATCC 7644) 4Aspergillus flavus (ATCC 9296) 4Brettanomyces bruxellensis (ATCC 10560) 4Escherichia coli (ATCC 11229) 5

S35A. Pascual et al. / Trends in Food Science & Technology 18 (2007) S29eS35

The IPPC Directive and the best available techniquesEuropean environmental legislation is increasingly re-

quiring polluting industries to move to clean technologies.The most important regulation in this respect is the Inte-grated Pollution Prevention and Control (IPPC) Directive96/61/EC, which has considerable relevance and far-reachingeffects for all European food manufacturers.

The IPPC directive attempts to encourage the BestAvailable Techniques (BATs). BATs are defined as tech-niques that enable competitive levels of quality and produc-tivity to be achieved and are noted for their greaterenvironmental efficacy. This could be the case of ozoneagainst other traditional cleaning and disinfection tech-niques. Therefore, the IPPC Directive could potentiallylead to an increased use of ozone in EU countries.

To be considered as a BAT, a technique must be evaluatedand environmental benefits associated must be demonstrated.Some EU programmes are promoting the investigation andvalidation of emerging clean technologies in order to includethem in the European Reference Documents on BATs (BREFdocuments) which are used for the state members to regulatethe industrial activities of the affected facilities. The EuropeanIPPC Bureau is responsible for organising an exchange ofinformation between Member States and the industries andproduces BAT reference documents (BREFs) (see web sitehttp://eippcb.jrc.es).

The LIFE PROJECT OzoneCIPThe ‘‘Ozone clean in place in food industries’’ project

(OzoneCIP) has been funded by the EC under the LIFE-Environment Programme (LIFE 05 ENV/E/000251). Thisproject aims to demonstrate the environmental benefitsobtained by the use of Clean In Place procedures basedon ozone techniques in place of the traditional techniques.Furthermore, as a result of the achievement of environmen-tal indicators, the classification of this technology as a BATand its widespread knowledge and implementation withinthe European food processing industries is expected.

Three European R&D centres located in three differentEU state members will implement the project: Ainia inSpain, Bionord in Germany and Gdansk University ofTechnology in Poland. The demonstration activities willfocus on dairy, brewery and winery sectors. Three foodcompanies belonging to each of the mentioned sectorswill provide their contribution from an industrial point ofview. Industrial partners are Domecq bodegas (wine process-ing), Inbev (beer processing) and Meiere-Genossenschafte.G. Langernhorn (dairy processing).

A three-year project was started in December 2005. Aprototype will be built in Ainia’s facilities to enable thesimulation of industrial CIP processes and assay processesbased on ozone. The results should demonstrate the envi-ronmental benefits of ozone as an alternative to traditionalchemicals and define environmental indicators to updateBAT reference documents. Also, non-environmental factors

that can affect its feasibility at industrial level will beconsidered.

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